It is known in the art to provide hydrophilic coatings with low friction (coefficient of friction of 0.3 or less) for medical devices such as catheters, balloon catheters, catheter introducers, and the like. When such low friction surfaces are used, devices having such surfaces slide easily within passageways such as arteries, veins, cannulae and other body orifices. A variety of methods are known for providing desirable low friction surfaces for medical devices.
For example, an outer portion of the medical device may be fabricated of a material having desirable low-friction properties such as TEFLON or other such materials. Unfortunately, combining particular low-friction materials with other desired properties for the medical device, such as flexibility, is often not possible.
For that reason, hydrophilic, lubricious coatings are known for medical devices to provide the desired anti-friction properties. One such coating may be formed from combinations of isocyanate, polyurethane, and polyvinylpyrrolidone (PVP). Other such coatings have been provided with combination of isocyanate and/or polyurethane in with polyethylene oxide) (PEO). Still further, combinations of isocyanate, polyols or polyamines, and PVP or PEO are known to provide the desired low-friction properties for medical device surfaces. As examples, such PVP and PEO-based coatings are disclosed in U.S. Pat. Nos. 5,160,790 and 5,179,174 to Elton.
While effective for their intended purpose, improvements in such coatings are possible. For example, polyvinylpyrrolidone-based coatings, while suitably flexible and lubricious, may abrade during use, exposing portions of the coated medical device and reducing the overall anti-friction properties of the coated device. Poly(ethylene oxide)-based coatings, while providing superior abrasion resistance, are not as soft and generally not as lubricious as polyvinylpyrrolidone-based coatings.
The present disclosure addresses a need in the art by providing hydrophilic, lubricious coatings for medical devices which, while providing the desired anti-friction properties, retain those anti-friction properties even in the event a portion of the coatings abrade during use. In particular, hydrophilic, lubricious coatings including a first layer comprising PEO and a second layer comprising PVP are disclosed. In the event the second, PVP-based layer abrades, the coated device retains its anti-friction properties due to the more durable, PEO-based first layer.